The 30fps cap in DKS was added to help with the stuttering issues some people had in the original release of D2:ED. It did in many cases, but not all, and it put that restriction on people who were not experiencing the stutter, so an option to change/remove the cap was added in a patch.
I'm not sure if there are any suggestion that were not in the links I posted in the Steam discussion above, but there are other relevant topics (one below).
stuttering due to camera linked to animation (there is no such link)
